Switchable optical filter apparatus with light

ABSTRACT

An apparatus comprising a switchable optical filter comprising a layer of switchable material, the switchable material comprising a photochromic/thermochromic, a photochromic/photochromic, or a photochromic/electrochromic compound; a first light source providing light of a wavelength that causes the switchable material to transition from a faded state to a dark state, or a dark state to a faded state; and a switch for controlling activation of the first light source.

RELATED CASES

This application is a National Stage Application of PCT/CA2013/000176,filed Feb. 22, 2013, which claims the benefit of U.S. ProvisionalApplication No. 61/602,203, filed Feb. 23, 2012, PCT/CA2012/000910 filedSep. 28, 2012, and PCT/CA2013/000054, filed Jan. 21, 2013, incorporatedherein by reference in their entirety. To the extent appropriate, aclaim of priority is made to each of these applications.

TECHNICAL FIELD

The present invention relates to an apparatus comprising optical filterand a light source. More specifically, the invention relates to anapparatus comprising a switchable optical filter and one or more lightsources, the switchable optical filter capable of switching between highand low visible light transmittance.

BACKGROUND

Photochromic materials react to light levels by darkening in sunlight(or other light having a UV component), and spontaneously reverting to afaded state under low light conditions, or indoors where the UV light isremoved. An example of a photochromic material is found in theTRANSITIONS™ lenses. U.S. Pat. No. 6,065,836 describes a photochromicopthalmic lens with a film comprising a photochromic dye. Both fadingand darkening are ‘passive’, in that they occur without input of a user,or in a controllable manner. Such materials may be less useful in anenvironment where UV is lacking, or variable, or where temperaturefluctuates. Such photochromic eyewear worn inside a vehicle on a brightday may have the darkening reaction inhibited by the low amount of UVlight in the vehicle (e.g. caused by UV blocking PVB layer of thewindshield). Conversely, the glasses may go dark when a user does notwish them to.

Thermochromic materials respond to temperature—US 2009/0167971 describesan optical filter comprising a liquid crystal material that isthermochromic—when used as a window film, it may be useful inattenuating heat gain in a building under some conditions, but may notbe controllable to provide full light transmission under highertemperature conditions. The temperature dependent darkening and fadingis passive, and may occur without the input of a user, or in acontrollable manner. Such materials may be less useful where temperaturefluctuates, where a dark state is desired in a low temperatureenvironment, or where a faded state in a high temperature environment isdesired.

Electrochromic materials respond to application of electricity. Someelectrochromic materials (e.g. bipyridinium-group containing materials)darken with application of a voltage, but fade passively when theapplication ceases. Such materials may employ a conductive layer such atITO to effect operation—where these materials are used as an overlay orunderlay for some configurations of displays (e.g. touchscreens),operation of the electrochromic material (e.g. providing an electricvoltage to the conductive layer of the electrochromic material) mayinterfere with operation of a touchscreen. The applied voltage to inducethe color change may vary with the nature of the material, from a fewvolts to as much as 60V or 120V to effect the transition between darkand faded states. Some electrochromic materials may require continuousapplication of electricity to maintain their dark or faded states.

Some switchable materials may provide controllable darkening, such aselectrochromic, liquid crystal or suspended particle materials, but mayhave other disadvantages such as cost, lack of optical clarity, reducedlifetime or haze, or may be difficult to adapt to some applications(e.g. incorporation into safety glass by lamination with PVB).

Controllable darkening may be useful not only for glazings or opthalmicapplications, but for reducing or blocking light from displays. In someapplications, it may be desirable for the display to be ‘blacked out’when not in use. Some embodiments may overlay a device with a tintedglass with a low visible light transmittance to appear black when not inuse. When it is desired to view the display or interact with thetouchpad, the display screen behind the tinted glass is illuminated witha light source to visualize icons, images or the like on the display.Depending on the degree of tint of the tinted glass, the luminancenecessary to make the display visible to a user may be substantial. Insome applications, the light source providing a suitable level ofluminance may represent a considerable power draw, and/or generateexcessive heat. If the display is in a confined space (e.g. a steeringcolumn or dashboard of a vehicle, control panel of an aircraft, or thelike), or used in a device that must carry or supply its own power (e.g.battery operated), the heat production and/or power draw may represent asubstantial engineering obstacle. Further, excessive heat production ina confined space may affect the operation of other instruments ordevice, such as computer controls.

SUMMARY

A device and/or method to overcome disadvantages in the art is needed.

The present invention relates to an optical filter with a light source.

In accordance with one aspect, there is provided an apparatus comprisinga switchable optical filter comprising a layer of switchable material,the switchable material comprising a photochromic/thermochromic, aphotochromic/photochromic, or a photochromic/electrochromic compound; afirst light source providing light of a wavelength that causes theswitchable material to transition from a faded state to a dark state, ora dark state to a faded state; and a switch for controlling activationof the first light source.

In accordance with another aspect of the invention, there is provided adisplay apparatus comprising: a display; and a switchable optical filtercomprising a layer of switchable material, the switchable materialcomprising a photochromic/thermochromic, a photochromic/photochromic, ora photochromic/electrochromic compound.

The apparatus, or display may further comprise one or more UV blockinglayers, or one or more light dispersing (light transmitting) layers. AUV blocking layer may block light of less than about 420 nm, or lessthan about 400 nm, or less than about 390 nm, or less than about 380 nm,or less than about 370 nm, or less than about 360 nm.

The apparatus or display may further comprise a second light source.

The switching material may comprise a compound selected from a groupcomprising: diarylethenes, dithienylethenes, fulgides, hexatrienes,cyclopentadienes, azobenzenes, spiropyrans, spirooxazines, polymerscomprising one or more of such organic molecules, conjugated polymers,or metal oxides (e.g. WO₃, TiO₂ or the like). The switching material maycomprise a photochromic/electrochromic compound. The switching materialmay comprise a compound according to Formula I, Formula II or Formula Iand II. The switching material may be thermally stable in both a darkstate and a faded state.

The first, the second, or the first and the second light sources mayprovide light in the UV or VIS range. In some aspects, the light may beof less than 450 nm, or from about 350 to about 450 nm, or from about380 to about 420 nm, or any amount or range therebetween. In someaspects, the light may be from about 450 to about 750 nm, or from about450 to about 650 nm, or from about 575 to about 650 nm, or any amount orrange therebetween.

The optical filter may be transitionable from a faded state to a darkstate with application of 350 to 420 nm light, and transitionable from adark state to a faded state with application of 450 to 650 nm light, orlight with a wavelength of from about 575 to about 650 nm, orelectricity. In some aspects, the switchable optical filter may betransitionable from a faded state to a dark state with application of350 to 420 nm light, and transitionable from a dark state to a fadedstate with application of 450 to 650 nm light, or light with awavelength of from about 575 to about 650 nm, or electricity. In someaspects, the switchable material may comprises a compound according toFormula I and a compound according to Formula II, and is transitionablefrom a faded state, to a dark state of 1% or less light transmittancewith application of UV light.

In some aspects, the first, second or first and second light sources maybe adjacent to one or more edges of the switchable optical filter, oradjacent to one or more surfaces of the switchable optical filter, or ata periphery of the optical filter. In some aspects the first lightsource, the second light source or the first and the second lightsources are on a plane parallel, or substantially parallel to thedisplay. The optical filter may be spaced apart, or in contact with, asurface of the display. The display may be backlit, edgelit or backlitand edgelit by a light source.

The apparatus may be used in a display, opthalmic device, architecturalinstallation, wall, glazing, vehicle, dashboard or other control panel.The display may be configured to display information relevant tooperation of a vehicle, instrumentation of a vehicle, and/or acontroller for controlling instrumentation of a vehicle.

The display may comprise a liquid crystal display (LCD), an OLED displayor an electroluminescent liquid crystal display; the OLED display may betransparent and/or flexible. The display may be an interactive display,and/or may be configured to receive user input and/or provide a usertactile feedback. The display may comprise a touchscreen, such as

The display apparatus of claim 30 wherein the display comprises atouchscreen such as a resistive touchscreen, a capacitive touchscreen, asurface wave touchscreen, an infrared touchscreen a dispersive signaltouchscreen or an acoustic pulse recognition touchscreen.

The apparatus of claim 1 wherein the switchable optical filter istransitionable to a variable light transmittance of about 0 to about 5%on exposure to light of a first wavelength, and to a light transmittanceof from about 30% to about 90% on exposure to light of a secondwavelength.

The switchable optical filter comprising a light source may be adaptedto retrofit an existing display by application of the switchable opticalfilter to a surface of the display. The light source may be connected tothe vehicle's electrical system; a switch may further be provided tooperate the light source as desired.

This summary of the invention does not necessarily describe allfeatures. Other aspects, features and advantages will become apparent tothose of ordinary skill in the art upon review of the followingdescription of specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the followingdescription in which reference is made to the appended drawings wherein:

FIG. 1 shows a sectional view of an apparatus according to oneembodiment.

FIG. 2 shows a detail view of a portion of the apparatus of FIG. 1.

FIGS. 3-6 a, b shows a sectional view of an apparatus (display withlight source and switchable optical filter) according to variousembodiments.

FIG. 7a, b show sectional views of an apparatus (photochromic eyewearwith light source) according to further embodiments.

FIG. 8 show sectional views of an apparatus (display) according toanother embodiment.

FIG. 9 shows a sectional view of an apparatus (display and remote lightsource) according to another embodiment.

FIG. 10 shows a sectional view of an apparatus (display with lightsource) according to another embodiment.

FIG. 11 shows a sectional view of an apparatus (vehicle glazing)according to another embodiment.

FIG. 12 shows a sectional view of an apparatus (architecturalinstallation) according to another embodiment.

FIG. 13 shows transmission spectra of an optical filter comprising aswitching material. Dotted line—transmission in faded state; dashedline—transmission in dark state (solar simulator light source); solidline, transmission in dark state (UV-only light source), according toanother embodiment.

DESCRIPTION

The present disclosure describes, in part, an apparatus comprising aphotochromic switching material that may be controllably darkened.Control of fading, darkening or both fading and darkening may beaccomplished by a light source that may be controlled to stimulate theswitching material with light (electromagnetic radiation) of a suitablewavelength to alter the light transmissibility of the material in acontrollable manner. The light source may be selected to provide lightin the UV, VIS and/or IR range, or a portion thereof, as may be suitablefor the switching material, and the intended transition (dark to fadedstate, or faded to dark state). The light source may be integrated intothe apparatus in a variety of ways as described or illustrated herein.In some embodiments, filters that selectively transmit or excludeselected wavelengths of light may be included in the apparatus.

In some embodiments, the apparatus may provide controllable darkening ofthe switching material in situations where darkening would not occurpassively (e.g. indoors, vehicle interiors). In some embodiments, theapparatus may be incorporated into a device or system to control thebrightness or visibility of a display, or display elements. In someembodiments, the apparatus may provide for controlled darkening of aphotochromic/electrochromic glazing that may be used in architectural orvehicle applications. Exterior glazings may be darkened at night (whenno daylight is present); interior glazings may be controllably darkenedwhen exposure to sunlight is not available.

The disclosure provides, in part, an apparatus comprising a switchableoptical filter, a first light source and optionally a second lightsource, the light sources configured to provide light to the opticalfilter. The apparatus may be configured for use with a display.

A switchable optical filter according to various embodiments of theinvention may be cycled between dark and faded states by exposure toselected first and second wavelengths of light, light and heat, or lightand electricity. The optical filter may further be thermally stable, orunresponsive to a range of temperatures. The optical filter, and/or adevice comprising such an optical filter, viable for a variety ofapplications including opthalmic devices (e.g. visors, masks, goggles,lenses, eyeglasses (prescription or not) or the like), architecturalwindows, architectural installations such as a wall (e.g. partition,divider, full or partial wall, permanent or temporary wall), display(e.g. illuminated information panels, touchscreens, control panels),vehicle window or glazing, and vehicle sunroofs of various typesincluding pop-up, spoiler, inbuilt, folding sunroofs, panoramic roofsystems or removable roof panels. Electrical power to illuminate a lightsource may be provided by a separate battery, or the optical filter maybe connected to an electrical system of the device (e.g. it may be wiredinto a vehicle's electrical system). The optical filter may demonstraterapid switching between dark and light states, which may be advantageousin applications where frequent or rapid changes in lighting conditionsoccur, for example automotive applications, display applications oropthalmic applications. The optical filter may exhibit minimal or nochange in light transmittance in response to temperature, which may beadvantageous in applications where frequent or rapid changes intemperature conditions occur, for example automotive applications,display applications architectural applications or opthalmicapplications. The optical filter may be stable in that switching from adark to a faded state, and/or from a faded to a dark state, does notoccur unless the appropriate light source is applied (a bistable opticalfilter). The optical filter may exhibit photostability and durabilitysuitable for use in various applications, including those referencedherein, and may be cycled between light and dark states many times.

Light transmittance (LT) of an optical filter may be controlled bycontrolling the light to which the optical filter is exposed. Theoptical filter may be exposed to UV light continuously, intermittentlyor as a single ‘dose’ for a defined period of time (e.g. controlled byan operable switch and optionally with a timer to turn the switch off oron after a defined period of time; the operable switch may be operatedby a user, or by a control circuit) to switch the optical filter or tomaintain the optical filter in a faded or a dark state.

The disclosure further provides, in part, a display apparatus(“display”) comprising a display and a switchable optical filter, theswitchable optical filter adjacent to, or offset from, a surface of thedisplay by a suitable distance. The display may further comprise a firstlight source, and optionally a second light source, the first, second orfirst and second light sources configured to provide light to theswitchable optical filter and/or the display.

A display may be used in a variety of applications to convey words,images or information to a viewer. Vehicle dashboards, steering columndisplays, video screens of various configurations, household appliance,monitors, control panels or the like may use one or more of LCDtechnology, organic light emitting diode (OLED), cathode ray tube (CRT),backlighting, edgelighting or the like to portray the intendedinformation. Edge lighting may be facilitated by a light source alongone or more edges of the apparatus (a peripheral light source), oroptical filter of the apparatus. Such displays may be further coupledwith an interactive aspect, such as capacitive touch or resistive touch,so that a user may interact with the display and make selections,control aspects of the device or other devices to which thedisplay/control panel is linked. A display may be transparent, flexibleor transparent and flexible. A display may be transparent to VIS light,but not to UV light. A display may have an interactive aspect (e.g.resistive touchscreen, capacitive touchscreen, or the like).

A variable transmittance optical filter (switchable optical filter) hasa light transmittance that is variable upon application of a stimulus,the stimulus may be light or electricity, or both light and electricity.A switchable optical filter comprises a first, and optionally a second,substantially transparent substrate and a layer of switching material.The first and second substrates may each be rigid or flexible; where thefirst and second substrates are flexible, the switching material mayalso be flexible. The switching material may be transitionable from afirst light transmittance state to a second light transmittance statewith application of one or more of UV or VIS light; the switchingmaterial may be stable in a faded state and not undergo thermaldarkening; the switching material may be stable in a dark state and notundergo thermal fading.

A switchable optical filter may comprise one or more layers of switchingmaterial applied to a substrate, or between first and second substrates.In some embodiments, the switching material may be applied to a surfaceof a display (e.g. applied to the clear glass or plastic of thedisplay), or may be mounted adjacent to and offset from, a surface ofthe display. An optical filter comprising two or more layers ofswitching material may further comprise a transparent layer between thelayers of switching material. The transparent layer may be a lightdistributing layer. A light distributing layer may be transparent orsubstantially transparent to light perpendicular to the layer. In someembodiments, the light distributing layer is optically clear, orsubstantially optically clear. The light distributing layer maydistribute light across the optical filter (from one side to another) toilluminate the switching material and effect a transition from faded todark state, or from dark to faded state. The light transmitted throughthe light transmitting layer may be provided by a light sourceintegrated into the optical filter. Illumination of the switchingmaterial may be provided by one or more light sources along one or moreedges, along one or more planes, or along one or more edges and one ormore planes of the optical filter. A light distributing layer may conveylight from an edge light source across the switching material.

An illuminated display, for example a display mounted in a vehicle (e.g.dashboard, steering column, seat back or the like) may be useful inproviding information, and/or a controller or controlling means forcontrolling operations of a vehicle (e.g. touchscreens or the like). Thebrightness of such a display may be manually adjusted by a user, or asensor that detects the ambient lighting intensity may provide a signalto a control circuit to dim or brighten the display as appropriate, tofacilitate viewing. When visualization of the display is not needed ordesired, the illumination source may be switched off, however there maybe residual lighting, ‘screen burn’, or the existing colour of thedisplay that prevents a uniform dark, or ‘blackout’, appearance frombeing achieved. To achieve a uniform dark appearance, an optical filtermay be placed in front of the display, the optical filter transitionablefrom a light state to a dark state on exposure to light of a firstwavelength, and from a dark state to a light state on exposure to lightof a second wavelength.

Referring to FIGS. 1 and 2, an apparatus according to some embodimentsis shown generally at 10. A switchable optical filter 12 comprising afirst substrate 14, a second substrate 16 and a layer of switchingmaterial 18 disposed between first and second substrates has a lightsource 20; the light source may surround the edge of the apparatus (e.g.a circumferential light source) or may be along only a subset of sidesof the apparatus; the light source may further be connected to a powersource (not shown). Frame 23 may surround the optical filter and lightsource. Electrical connectors (not shown) connecting the light source(s)to a source of voltage may be contained within the frame. In someembodiments frame 23 may comprise a reflective component on an insidesurface, and may reflect light from the light source towards the layerof switching material 18. Surface 22 of substrate 16 may have a layerapplied thereto, the layer may selectively block or transmit lightincident on the apparatus. The layer may be a UV blocking layer, or acoloured layer (a static filter) to selectively transmit visible lightof selected colour, or an anti-glare, anti-scratch, anti-reflective orother layer. The layer may be a component of substrate 16, or may be aseparately-applied layer. In some embodiments, the frame may surroundthe edges of a display upon which the optical filter is fastened, orrests. The light source 20 may provide a first, a second or both firstand second wavelengths of light (e.g. from separate light emittingdiodes (LEDs) or LED arrays) across the switching material, and, throughthe layers of the optical filter and display. A control circuit maycontrol the light source(s) so that when a light source providing afirst wavelength of light is on, a light source providing a secondwavelength is off, and vice versa. The control circuit may furthercomprise a switch, and may be connected to an electrical system of avehicle to provide power to the LEDs. FIG. 2 shows a detail view of theapparatus of FIG. 1. The detail view shows 3 light sources (which may bearranged in rows along the edges of the optical filter), however otherconfigurations of 1, 2 or more rows or arrays of light sources are alsocontemplated.

Referring to FIG. 3, an apparatus according to another embodiment of theinvention is shown generally at 30. A display 24 has an optical filter12 comprising first and second substrates and a layer of switchingmaterial therebetween applied to a surface. A housing 31 surrounds theoptical filter and contains light sources 32 a, 32 b and 20, along withcontrol circuitry and electrical connectors for operation of the lightsource and controllable illumination of the optical filter. Lightsources 32 a, b, providing illumination through the layers, includingthe optical filter and display, light sources 20 provide illuminationacross the optical filter from the side. A light transmitting layer (notshown) may further be included in the apparatus. The display may furtherhave a UV blocking layer applied to one or more surfaces; such assurface 33. In some embodiments, light source 20, 32 a,32 b may providethe same, or different type of light. Light sources 20, 32 a, 32 b maycomprise an array of light emitting diodes (LEDs), providing light of afirst, and optionally a second wavelength. Light source 32 a, b may be aplanar array of LEDs or OLED. In some embodiments, light source 32 a, bmay be a planar LED light, or OLED. Light source 20 may be a lineararray of LEDs, of one, two or more rows. The housing may furthercomprise mounting o fastening components (nuts, bolts, fasteners or thelike) for mounting the housing comprising the optical filter and displayin a panel, such as a dashboard or other desired site.

Referring to FIGS. 4 and 5, an apparatus according to another embodimentof the invention is shown generally at 40. A display 24 comprises anoptical filter comprising a first switching material 18, a secondswitching material 34 and a substrate 14. The first and second switchingmaterials may each comprise switching compounds with complementary lightabsorption profiles. A surface 19 of substrate 14 may comprise a layerUV blocking layer, or a coloured layer (a static filter) to selectivelytransmit visible light of selected colour, or an anti-glare,anti-scratch, anti-reflective or other layer. The layer may be acomponent of substrate 14, or may be a separately-applied layer. Lightsource 32 may provide illumination through the optical filter anddisplay. Light source 32 may comprise an array of first 32 a and second32 b LEDs. Light source 32 illuminates display 24, and also provideslight to illuminate and switch first and second switching materials.Light source 20 provides additional light to illuminate and switch firstand second switching materials. Light source 20 and LEDs 32 a, 32 b mayprovide the same, or different light. FIG. 5 illustrates a furtherembodiment at 42, placing the switching materials 18, 34 between thelight source 32 and display 24, also with peripheral light source 20.The first and second switching materials are in contact and may eachcomprise one or more components that are immiscible with the other. Acontrol circuit may control the light source.

Referring to FIG. 6a , an apparatus according to another embodiment ofthe invention is shown generally at 44. Display 24 is illuminated bylight source 32 a, 32 b, and is behind optical filters 18 a and 34 a,comprising switching material 18 and 34, respectively, with lighttransmitting layer 38 disposed therebetween. Peripheral light source 20provides light that is dispersed across the optical filter. Layer 38 istransparent to light from light source, and conducts light across theoptical filters so that both layer of switching material receive light;in some embodiments the light is UV light, or light in a wavelengthrange from about 350 nm to about 420 nm to darken the switchingmaterial, and VIS light or light in a wavelength range of from about 550nm to about 650 nm to fade the switching material. Light source 32 mayprovide additional light to fade the switching material. A controlcircuit may control the light source.

FIG. 6b shows another embodiment of the apparatus. Display 24 isilluminated by light source 32 a, 32 b, and is behind an optical filter12 comprising one layer of switching material. Optical filter 12 maycomprise a switching material with one, two or more chromophores. Lightsource 32 a, 32 b may provide first and second light sources,—inoperation, one or both of light sources 32 a, 32 b may illuminate thedisplay (e.g. backlit) and provide light to the optical filter to effectthe transition from a faded state to a dark state, or vice versa. Forexample, where light source 32 a provides light in a range of about 350to about 420 nm (e.g. UV light), and light source 32 b provides VISlight, or light in a range of about 450 to about 650 nm, turning onlight source 32 a may darken a switching material.

When light source 32 a is off and light source 32 b is on, the displaymay be illuminated and the switching material faded. Control circuitrymay be configured to alternate the light sources with the operation of aswitch, thus a user can darken the optical filter when the display isnot needed, and turn on the display and fade the optical filter when itis desired.

The embodiments illustrated in FIGS. 4, 5 and 6 a have first and secondlayers of switching materials. Multiple layers of switching material maybe advantageous where first and second switching materials have one ormore components that are immiscible or incompatible.

Referring to FIG. 7a , an apparatus (photochromic eyewear comprisingcomponents for controllable darkening) according to another embodimentis shown generally at 50. An optical filter comprising a substrate 53with surface 52, a layer of switching material 54, a light distributinglayer 55 and a layer 56 for selectively blocking UV light is affixed toa frame 58—substrate 53 may be a lens. A light source 60 may be embeddedwithin or mounted on the frame 58 to provide light to an edge of thelens, and to the switching material. The light source may be a UV lightsource, a VIS light source or both a UV and a VIS light source. Lightfrom the light source may be distributed across the switching material(through the lens) via the light distributing layer 55. Where lightsource 60 provides UV light, UV blocking layer 56 may protect a user'seyes from the light source.

Referring to FIG. 7b , an apparatus according to another embodiment isshown at 65. A light source 69 may be mounted on a front edge 58 a ofthe frame 58; front edge 58 a may extend beyond the front plane of thelens 52, and directs a portion of the light from light source 69 to thelens 52 comprising a switching material. In other embodiments, aninterior concave surface of front edge 58 a may comprise a reflectivematerial applied to a concave surface to further reflect light; lightdirector may comprise a downward directed front edge, which may bestraight or curved. In some embodiments, the light source may bedirectional, such that the light of the light source is directed towardsthe front plane of the lens. Where light source 69 provides UV light,the front surface of the lens may be configured to transmit light fromthe light source to the switching material (the front surface of thelens does not block, or at least partially transmits incident UV light)to control darkening of the switching material. In some embodiments aselective UV blocking layer may be applied to the front surface of thelens; the light source 69 may be selected to provide a wavelength orrange of wavelength of UV light that is not blocked by a UV blockinglayer.

Switch 62 is connected to the light source and a power source (battery,not shown) via electrical connector 63. The switch may be located in anyspot convenient for a user—in one embodiment, switch 62 is mounted on anarm 64 of the eyewear. A user may operate the switch to turn a UV lightsource on to darken the switching material (where the switching materialis UV-darkening), and turn the UV light source off when fading of theswitching material is desired. In some embodiments where the lightsource comprises a VIS light source, a switch may be operated to turn onthe VIS light source to fade the switching material. Fading may besupplemented by VIS light incident on the lens. In some embodiments, theintegrated light source may supplement external light for darkening orfading the switching material. An additional (optional) UV blockinglayer may be included on the side of the lens away from the user, toblock external UV light and reduce or prevent its influence on thedarkening or fading of the switching material. Where this additional UVblocking layer is present, the integrated light source may be theprimary, or only, source of stimulus to darken the lens, and the userwould have full control over darkening of the lens.

Referring to FIG. 8, an apparatus according to another embodiment isshown generally at 75. A display 80 comprising an optical filter 81 anda top layer 82 may be mounted in a vehicle dashboard 78, or othersurface configured for mounting a display. Light from a light source 76integrated into the dashboard 78 of a vehicle may be directed, orreflected, onto the switching material. Where the display is wide orlarge, the reflecting portion may facilitate the light reaching allareas of the switching material. In some embodiments, top layer 82 maybe colorless, and may further distribute light from the light sourceacross the switching material. In some embodiments, top layer may betinted and reduce the intensity of the light transmitted from thedisplay. In some embodiments, the top layer may comprise a UV blockinglayer; the light source may be selected to provide a wavelength or rangeof wavelength of UV that is not blocked by the UV blocking layer. Theswitching material may be darkened with UV light from the light sourceto dim the display as desired (e.g. when driving at night). Theswitching material may be faded with VIS light from the light source. Acontrol circuit may control the light source.

Referring to FIG. 9, another embodiment is shown generally at 85.Darkening or fading of the switching material in a display may beachieved by using a controllable light source located remotely from theswitching material. When light source 86 is on, light passes through acollimating filter 88 and collimated light 89 is directed only to theoptical filter 81 of the display 80. The light source may be located inthe ceiling or headliner of the vehicle cabin, for example. Thecollimating filter may focus light on the display, preventing unwanteddispersion of light from the light source through the cabin. Surface 87may be a tinted layer, or may be a UV or IR blocking layer.

Referring to FIG. 10, another embodiment is shown generally at 90. Adisplay 80 with an optical filter 81 and an adhesive layer 82 may bemounted on a panel or glazing, or other surface configured for mountinga display. In the embodiment shown in FIG. 10, the display and opticalfilter are undermounted with adhesive 82 to a glass panel 83; panel 83may be tinted or clear glass, and may be configured for an inset mountin a dashboard or under a table, or the like. The display 80 is backlitby light array 91 comprising first 92 and second 94 light sourcesproviding first and second types of light. In some embodiments the firstlight source 92 is a UV light source, and the second light source 94 isa VIS light source.

Second light source 94 provides, in addition to back-lighting for thedisplay, a source of VIS light for fading the switching material 81. Toplayer 82 may be a UV blocking layer, separating the interior of thevehicle from the UV light of first light 92. The display with lightsource, switching material and top layer may be installed in thedashboard (flush-mounted or under-mounted). Darkening of the switchingmaterial is fully controlled through the integrated light source 91.

Where a user desires the display to be turned off, the switchingmaterial may be transitioned into a dark state by turning on lightsource 92 and exposing the switching material to UV light, darkening theswitching material. Where the switching material comprises a bistablecompound (stable in the dark or faded state configuration, in theabsence of electrical or light stimulation), UV light mayneed to beapplied for only a short period of time (e.g. from one to a few minutes)to darken the material, and may then be switched off, thus saving power.A UV blocking top layer prevents UV light from escaping the display,thus protecting a user from exposure to UV light.

Referring to FIG. 11 an apparatus according to another embodiment isshown generally at 100. In this example, the optical filter 81 may belaminated between layers of glass or transparent plastic 102 a, 102 bwith adhesive polymer interlayer(s) 104 a, 104 b, providing a switchableglazing. The switchable glazing may be used in, for example,architectural or vehicle installations. In some embodiments theswitchable glazing may be used in an automotive sunroof. To transitionthe switchable material from a faded to a dark state, UV light may beprovided by light source 110 at one or more edges. Light source 110 maybe turned on or off as desired to controllably darken the switchableglazing, using a switch; the switch may be integrated with, orindependent of, the vehicle electronics. The apparatus further comprisesa light distributing layer 112 to direct light from the edge lightsource to the switching material. In the illustrated embodiment, theglazing may be darkened by exposure to external UV light, however wheresuitable external UV light is unavailable, the glazing may be darkenedas described, thereby giving the user control over the darkeningfunction. For mounting in a vehicle as a sunroof, the apparatus may beheld in position against overhangs 105 a, 105 b at a first edge byfasteners (not shown) along the bottom edge 106 of the apparatus. Lightsources 110 may be mounted in the roof 108 and connected to the vehiclepower supply by control circuitry (not shown).

If darkening from external light is not desirable, layer 102 a may beconfigured with a UV blocking layer. In another embodiment, one or bothof the transparent adhesive interlayers may be, or comprise, a UVblocking material (a UV blocking layer)

Referring to FIG. 12, an apparatus according to another embodiment isshown generally at 120. A partition comprising a switchable material maybe used to divide work spaces or cubicles, or form part of an interiorwall, to give persons on either side a controllable privacy glass. Anoptical filter 122 and a light distributing layer 124 are flanked by UVblocking layers 124 a, b. In some embodiments, a UV blocking layer maybe a layer of one or more adhesive polymers and the optical filter andlight distributing layers ‘sandwiched’ between layers of glass ortransparent plastic with the adhesive polymer. Light sources 126, 127inside a housing 128 along opposing sides of the layers are shown; lightsources may extend along other sides of the layers (not shown). Thehousing may form top and bottom bounds to the switching region of thepartition, or may also form side bounds (thus surrounding the switchableportion as a frame), with a non-switchable portion 140 below, thenon-switchcable portion may be transparent, or not. To providecontrolled darkening of the switching material, light distributing layer124 directs light from edge light sources through the glazing and to theswitching material. Light sources may be controlled by a switch 130. UVblocking layers constrain the UV light from the light sources within theglazing—this protects a user from exposure to the UV light, and may alsoblock ingress of external UV light (e.g. from a window), preventingpassive darkening of the glazing. Where it is desired to fade theglazing, the optical filter material may be exposed to VIS light from alight source along an edge, or where the switching material isphotochromic/electrochromic, fading may be effected by application ofelectricity.

A “light source” is a source of VIS, UV and/or infrared light (IR). Alight source may also provide full spectrum light. Light sources mayinclude natural or simulated sunlight (direct or indirect), or lightfrom a selected wavelength or range of wavelengths. The selectedwavelength or range of wavelengths may be selected by the nature of thelight source itself (e.g. LED, a lamp that produces light in aparticular range such as a UV lamp, xenon-arc lamp, low-pressure sodiumlamp, or may be selected through use of a cutoff filter, designed toeliminate light, or a percentage of light of a wavelength above or belowa cutoff wavelength, or between two cutoff wavelengths. In someembodiments, the light source may include one or more LEDs. In someembodiments of the invention, the light source may be configured toprovide light above or below a predetermined wavelength, or may providelight within a predetermined range. A light source may be used incombination with a filter, to selectively transmit or block light of aselected wavelength from the light source, thereby controlling the lightthat may be applied to the switching material of the optical filter. Alight source may be connected to a power source by one or moreelectrical connectors; an array of light sources may be connected to apower source in series or in parallel. A power source may be a battery,or a vehicle electrical system or a building electrical system. Thelight source may be connected to a power source via control electronics(control circuit); control electronics may comprise one or moreswitches. The one or more switches may be automated, or controlled by asensor, timer or other input, or may be controlled by a user, or acombination thereof. For example, a user may operate a switch to turn ona UV light source to darken a UV-darkening switching material; the lightsource may be applied on a constant basis until it is turned off, or itmay be pulsed (repeated on/off cycles) until it is turned off.Similarly, a VIS light source may be turned on to fade a VIS fadingswitching material. In other embodiments, a user may operate a switch toturn on a light source, and the light source remains on, or pulses, andthe light transmittance of the optical filter may be monitored by alight sensor. When a suitable light transmittance state is attained, thesensor operates a switch in the control circuit to turn the light sourceoff. In some embodiments, the light source may be switched from acontinuously-on state to a pulsed state, or vice versa. In someembodiments, fading or darkening may be supplemented by VIS lightincident on the optical filter (e.g. supplement fading for a VIS-lightfading material, supplement darkening for a VIS-darkening material).

In some embodiments, it may be preferable to prevent egress of light(for example UV light) from the optical filter—a UV blocking layer maybe included on a side of the optical filter, or apparatus. The UVblocking layer may also, or alternately, prevent ingress of external UVlight, and reduce or prevent its influence on the darkening or fading ofthe switching material. Where this additional UV blocking layer ispresent, an integrated light source (back-lit, or along an edge, orboth) may be a primary, or only, source of stimulus to darken the lens,and the user would have full control over darkening of the lens. In someembodiments, a first and a second light source may be coupled by acontrol circuit, such that when the first light source is off, thesecond light source is on, and vice versa.

In some embodiments, there may be a single layer of switching materialcomprising two or more switching compounds that are switchable in thesame switching material (e.g. soluble in the same matrix). In someembodiments, the optical filter may be adjacent to a surface of adisplay, and may be fastened by an adhesive layer, an encapsulatinglayer. In other embodiments, the optical filter may be spaced apart froma surface of the display by a suitable distance. The distance may bemaintained by one or more spacer elements. The distance or space mayaccommodate an air gap. In some embodiments, the distance may bemaintained by a clear material such as a polymer or adhesive layer. Theair gap and spacer elements may be configured to accommodate airmovement between the display and switchable optical filter.

In some embodiments where the switching material is aphotochromic/electrochromic material, where full control may be achievedeven in the absence of a UV blocking layer preventing incident UV lightfrom darkening the switching material. Darkening of the switchingmaterial may be accomplished by operation of a UV light source, incidentUV light or both. Fading may be accomplished by operation of a switchwith a second setting, or operation of a second switch, that applieselectricity to the switching material, or both. For such an embodiment,the switching material is in contact with first and second electrodes(for conduction of electricity from a power source through the switchingmaterial), and a user has full control over the light transmissibilityof the switching material (or lens, display or glass comprising theswitching material), regardless of whether UV light is available or notfrom an external source.

For embodiments comprising a UV light source, a UV blocking layer may beplaced between a source of UV light and a user, to prevent exposure of auser to UV light, and/or to prevent switching of the film or article inresponse to an external light source, when such switching isundesirable.

“Visible light” (VIS) generally refers to the band of electro-magneticradiation with a wavelength from about 400 nm to about 750 nm.“Ultraviolet (UV) light” generally refers to electromagnetic radiationwith a wavelength shorter than that of visible light, or from about 10nm to about 400 nm range. In some embodiments, there may be overlap inthe general ranges of VIS and UV light, and UV light may be consideredto include light with a wavelength up to about 420 nm. In someembodiments, sub-ranges of ultraviolet light may be used, and/or mayoverlap with light in the visible range, for example from about 100 toabout 420 nm, or from about 200 to about 420 nm, or from about 300 toabout 420 nm, or from about 350 to about 420 nm. “Infrared light” orinfrared radiation (IR) refers to electromagnetic radiation with awavelength greater than the VIS range, or from about 750 nm to about50,000 nm. Light may also be described with reference to colour or rangeof wavelength. Light from a light source may be from about 350 to about750 nm, or any amount or range therebetween, for example from about 350nm to about 360, 370, 380, 390, 400, 410, 420, 430 or about 450 nm, orany amount or range therebetween. In other embodiments, light from alight source may be from about 550 to about 700 nm, or any amount orrange therebetween, for example from about 550 to about 560, 570, 580,590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690 or about 700 nm,or any amount or range therebetween.

Optical filters according to various embodiments of the invention may bedescribed with reference to clarity or haze, translucency, transparencyor opacity, light transmittance (LT), switching speed, durability,photostability, contrast ratio, state of light transmittance (e.g. darkstate or light state) to further define the device or apparatus, oraspects of the device or apparatus; some values or characteristics ofsuch descriptors may be applicable to some or all devices, but onlyexemplified in one type of device; alternately, some values orcharacteristics of such descriptors may be applicable to only a fewtypes of devices.

“Light transmittance” (LT) refers to the quantity of light that istransmitted or passes through an optical filter, or device or apparatuscomprising same. LT may be expressed with reference to a change in lighttransmission and/or a particular type of light or wavelength of light(e.g. from about 10% visible light transmission (LT) to about 90% LT, orthe like). An object with a higher LT transmits more visible light. LTis expressed as a number or range between 0 and 1, or as a percentage (0to 100). LT may alternately be expressed as absorbance, and mayoptionally include reference to one or more wavelengths that areabsorbed. According to some embodiments, an optical filter may beselected, or configured to have in the dark state, a LT of less than80%, or less than 70%, or less than 60%, or less than 50%, or less than40%, or less than 30%, or less than 20% or less than 10%, or any amountor range therebetween. According to some embodiments, an optical filtermay be selected, or configured to have in the light state, a LT ofgreater than 80%, or greater than 70%, or greater than 60%, or greaterthan 50%, or greater than 40%, or greater than 30%, or greater than 20%or greater than 10%, or any amount or range therebetween. According tosome embodiments an optical filter may have a LT of less than 1% in thedark state, and have a LT of about 5 to about 50% in the faded state, orany amount or range therebetween. According to some embodiments, anoptical filter may have a LT of from about 2% to about 10% in the darkstate, and a LT of from about 5% to about 30% in the faded state, or anyamounts or ranges therebetween. The LT of each of the optical filtersmay independently be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20,25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95%, or anyamount or range therebetween, with the proviso that the dark state of anoptical filter has lesser LT than the light state of the same opticalfilter. For an apparatus comprising two or more optical filters, or twoor more layers of switching material, the LT of the individual opticalfilters or layers of switching material may be additive to provide theLT of the optical filter. LT may be measured as an average lighttransmittance across a visible range (VLT) or may be weighted LightTransmittance (Illuminant A) or LT_(A).

A switching material may darken, or reach a dark state when exposed tolight of a first wavelength, and may fade, or reach a faded state whenexposed to light of a second wavelength. In some embodiments a switchingmaterial may fade when a voltage is applied. In some embodiments, theswitching material may fade upon exposure to selected wavelengths of VISlight and darken upon exposure to selected wavelengths of UV light. Darkstate and faded state may be described relative to each other.

Contrast ratio is a ratio of the LT of an optical filter in the fadedstate and the dark state. For example, an optical filter may allowtransmission of about 10% of the visible light (˜10% LT) in a darkstate, and about 60% of the visible light (˜60% LT) in a faded state,providing a contrast ratio of about 6 (6:1). According to variousembodiments of the invention, a switching material may have a contrastratio of from about 2 to about 1000 or more, or any amount or rangetherebetween.

Clarity may be affected by haze due to cloudiness caused by scatteringof light. Light may be scattered by particles that are suspended in thesubstance. Haze may be measured by methods known in the art, forexample, using a “hazemeter” (e.g. XL-211 Hazegard, BYK Gardner),according to known and/or standardized methods. Optionally, the haze ofan optical filter according to various embodiments is between about 0%and about 5%. In some embodiments of the invention, the optical filterhas a haze transmission of about 5% or less, about 3% or less, about 2%or less, about 1.5% or less, or about 1% or less, or from 0-5%, 0.5 to3% or the like.

“Switching time” (“switching speed”) refers to the time necessary for anoptical filter to transition from a dark state to a clear state, or froma clear state to a dark state, or to alter light transmission by adefined amount (e.g. 60% to 10% LT in 5 minutes). An optical filteraccording to various embodiments of the present invention will have adarkening time of between about 1 second and 5 minutes to reach about10% of the LT of the dark state from the lightened state, and alightening time of between about 1 second and 5 m minutes to reach about90% of the LT of the light state from the darkened state. In someembodiments of the invention, the darkening time and lightening time ofan optical filter are independently about 1 to about 30 seconds, toabout 1, 2, 3, 4 or 5 minutes, or any amount of time or rangetherebetween.

The term “mil” as used herein, refers to the unit of length for 1/1000of an inch (0.001). One (1) mil is about 25 microns; such dimensions maybe used to describe the thickness of an optical filter or components ofan optical filter, according to some embodiments of the invention. Oneof skill in the art is able to interconvert a dimension in ‘mil’ tomicrons, and vice versa.

As used herein, the term “about” refers to a +/−20% variation from thenominal value. It is to be understood that such a variation is alwaysincluded in a given value provided herein, whether or not it isspecifically referred to.

Substrate

A substrate provides sufficient structural integrity to support theswitching material. The substrate may be optically clear, or translucentor opaque; the substrate may be tinted or untinted. Where the substrateis tinted, it may have a light absorbance profile in the VIS range thatis complementary to that of the switching material, the combination oftinted substrate and switching material may, in the dark state, blockall, or substantially all, light in the VIS range. The substrate may berigid or flexible—an optical filter comprising flexible substrate(s) maybe in the form of a film that may be applied to a rigid material, suchas a pane of a window, or a lens. One or more substrates of an opticalfilter may be made of any suitable material independently selected froma group comprising glass or plastic. Glass includes float glass,tempered glass, laminated glass, tinted glass, mirrored glass,reinforced glass, monolithic glass, multilayered glass, safety glass,bullet-resistant glass or “one-way” bullet-resistance glass. Plasticsinclude polyesters (PE), polycarbonates, polyamides, polyurethanes,polyacrylonitriles, polyacrylacids, (e.g. poly(methacrylic acid),including polyethylene terephthalate (PET), polyolefins (PO) orcopolymers or heteropolymers of any one or more of the above, orcopolymers or blends of any one or more of the above withpoly(siloxane)s, poly(phosphazenes)s, or latex. Examples of polyestersinclude homopolymers or copolymers of aliphatic, semi-aromatic oraromatic monomeric units, for example polycondensed 4-hydroxybenzoicacid and 6-hydroxynapthalene-2-carboxylic acid (VECTRAN™), polyethylenenapthalate (PEN), polytrimethylene terephthalate (PTT), polybutyleneterephthalate (PBT), polyethylene terephthalate (PET),polyhydroxyalkanoate (PHA), polyethylene adipate (PEA), polycaprolactone(PCL) polylactic acid (PLA), polyglycolic acid (PGA) or the like.Examples of polycarbonates include bisphenol A, polycarbonate or thelike. Other plastics include polyethene (PE), polypropylene (PP) and thelike. The substrate may, in some embodiments, have UV, IR or VIS lightblocking characteristics, or comprise a UV, IR or VIS light blockingagent or component. Other substrate materials include ceramic spinel oraluminum oxynitride.

The substrate may be of uniform or varying thickness, and of anysuitable dimension to provide sufficient structural integrity to supportthe switching material; determination of a suitable material andthickness is within the ability of one of skill in the art. For example,the substrate may have a thickness from about 0.01 mm to about 10 mm, orany amount or range therebetween, for example 0.05, 0.1, 0.5, 1, 2, 3,4, 5, 6, 7, 8, 9 or 10 mm, or from about 0.012 mm to about 10 mm, orfrom about 0.5 mm to 10 mm, or from about 1 mm to 5 mm, or from about0.024 mm to about 0.6 mm, or from about 0.051 mm (2 mil) to about 0.178mm (7 mil). In some embodiments, the thickness and/or material of thefirst substrate differs from the thickness and/or material of the secondsubstrate.

Switching Material

A switching material is transitionable from a light state to a darkstate on exposure to light of a first wavelength, or range ofwavelengths, and from a dark state to a light state with application ofa voltage, or on exposure to visible light of a second wavelength orrange of wavelengths. A first range of wavelengths (including light of afirst wavelength) includes light of from about 350 nm to about 420 nm,or any amount or range therebetween. A second range of wavelengths(including light of a second wavelength) includes light of about 450 nmto about 690 nm, or any amount or range therebetween. A switchingmaterial may further comprise one or more compounds having bothphotochromic and electrochromic properties. The switching material maybe optically clear. In some embodiments, the switching material may be aliquid, a solid, a semi-solid, a sol-gel or a gel. The liquid, sol-gelor gel may be of a range of viscosity. The thickness of the layer ofswitching material may affect the light transmittance of the compositeoptical filter. For example, when comparing a thinner and a thickerlayer of the same switching material, the thicker layer may provide adarker state (lower light transmission) Thickness may be uniform ornon-uniform. Within a composite optical filter, first, second and/orsubsequent layers of switching material may be of the same or differentthicknesses. Thickness of a switching material may be from about 0.5 milto about 10 mil, or any amount or range therebetween, for example, 0.5,1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5or 10 mil, or any amount or range therebetween.

The switching material may comprise one or more compounds (chromophores)and one or more solvents. Chromophores may include diarylethenes,dithienylethenes, fulgides, hexatrienes, cyclopentadienes, azobenzenes,spiropyrans, spirooxazines, polymers comprising one or more of suchorganic molecules, conjugated polymers, metal oxides (e.g. WO₃, TiO₂ orthe like), or the like. Other examples of compounds include themolecules and polymers described in WO02/06361, WO2004/015024,WO2006/125317 and WO2010/142019. Some examples of diarylethene moleculesproviding various colours in the closed-ring configuration that may beuseful in various embodiments of the invention are described in Irie2010. Proc. Jpn. Acad. Ser B 86:472-483; and Yamaguchi 2010 J PhotochemPhotoBiolA 213:141-146.

In some embodiments, the chromophore of a switching material is anorganic species having ring-open and ring-closed isoforms (A and Bisoforms), and is reversibly interconvertible between isoforms withapplication of light and/or voltage, respectively.

In some embodiments, the switching material may comprise one or moreadditional components. Additional components include one or more of asupporting electrolyte, a polymer, a charge compensator, a chargecarrier, a UV stabilizing agent, a UV blocking agent, a tinting agent,or the like. Some components may be able to fill more than one role inthe switching material, for example, certain compounds mayself-polymerize and fulfill the role of both dye and polymer (see forexample, compounds of WO2004/015024 and PCT/CA2012/000910); somepolymers may also have UV blocking capabilities; or the like. Somepolymers may be a rheology modifier, a cross-linkable polymer, or both arheology modifier and a cross-linkable polymer, or both. Conversely, insome embodiments, a given component may be made up of several individualcompounds, e.g., the polymer component may be a copolymer comprisingdifferent monomeric units.

Chromophores according to various embodiments may be selected fromFormula IA/B and Formula II A/B. In some embodiments, Conversion betweenisomers may be light-induced, or may occur under some oxidativeconditions such as electrochemical conditions as a result of applicationof a voltage, or a combination thereof. One or more chromophores maycomprise from about 1% to about 25% (by weight) of the switchingmaterial, or any amount or range therebetween, for example, 2, 3, 4, 5,6, 8, 10, 12, 15, 20 or 24 wt %, or any amount or range therebetween.For switching materials comprising two chromophores, they may be presentin about a 1:1 ratio (wt), or from about a 10:1 to about a 1:10 ratio,or any amount or range therebetween.

whereinX may independently be N, O or S;Z may independently be N, O or S;

Each R₁ may be independently selected from the group consisting of H,halo;

Each R₂ may be independently selected from the group consisting of H,halo, a polymer backbone, alkyl or aryl; or, when both R₂ together form—CH═CH— and form part of a polymer backbone;

Each R₄ may be independently selected from the group consisting of

Each R₅ may be independently selected from the group consisting of H,halo, alkyl or alkoxy. and;

Each of R_(6a), R_(6b), R_(6c), R_(7a), R_(7b) and R_(7c) may beindependently selected from a group comprising one or more of H, halo,alkyl, alkoxy, carbonyl, siloxy, thioalkyl or aryl. The R_(6a) andR_(7a) position may alternately be referred to as the “5 position”; theR_(6b) and R_(7b) position may alternately be referred to as the “4position”; the R_(6c) and R_(7c) position may alternately be referred toas the “3 position” of the ring;

Each of R_(9a), R_(9b), R_(9c), R_(9d) and R_(9e) may be independentlyselected from the group consisting of H, halo, alkyl, alkoxy, thioalkyl,carbonyl, siloxy or aryl.

In another aspect, R_(6a) and R_(6b), or R_(6b) and R_(6c) are each—CH═CH— and joined to form an unsaturated ring,

In another aspect, R_(7a) and R_(7b), or R_(7b) and R_(7c) are each—CH═CH— and joined to form an unsaturated ring.

In another aspect, R_(9a) and R_(9b), or R_(9b) and R_(9c), or R_(9c)and R_(9d), or R_(9d) and R_(9e) are each —CH═CH— and joined to form anunsaturated ring.

In another aspect, R_(9c) may be an alkyl, alkoxy or siloxy group,selected from a group comprising an alkyl group comprising from one to20 carbons. In another aspect, one or more of R_(10a), R_(10b), R_(10c),R_(10d) may be an alkoxy or siloxy group, comprising from one to tenoxygen atoms and from one to 20 carbons. In another aspect, an R_(10b)and an R_(10c) are each O, and joined with a —CH₂— to form a 5 memberedring.

As used herein, “halogen” refers to F, Cl, Br or I. The term “halo” isgeneric, and refers to any halogen moiety, for example fluoro- chloro-,bromo- or iodo-, or the like.

As used herein, “metal” as used herein refers to a transition metal, oran alkali metal such as Li, Na, K, or the like; or a metalloid such as Bor Si, or the like.

As used herein, “alkyl” refers to any linear or branched, non-aromaticmonocyclic or polycyclic, substituted or unsubstituted alkyl group of 1to 50 carbons, for example 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 25, 30, 35, 40, or 45, or any amounttherebetween. Examples of alkyl groups include methyl, ethyl, propyl,isopropyl, butyl, iso-butyl, sec-butyl, tert-butyl, 1-pentyl,iso-pentyl, neo-pentyl, hexyl, cyclopropane, cyclobutane, cyclopentane,cyclohexane or the like. The alkyl group may have one or more saturatedor unsaturated bonds. The alkyl group may contain only carbon andhydrogen atoms, or may further incorporate one or more heteroatoms suchas Si, N, O or S as part of the alkyl group (a heteroalkyl group).Examples of cyclic heteroalkyl groups include aziridine, oxirane,thiirane, oxaziridine, dioxirane, azetidine, oxetane, thietane,diazetidine, dioxetane, dithietane, azirine, oxirene, thiirene, azete,oxete, thiete, dioxete, dithiete, pyrrolidine, oxolane, thiolane,borolane, silolane, dithiolane, dioxolane, oxazolidine, piperidine,oxane, thiane, piperazine, morpholine or the like. An alkyl group with aSi heteroatom may be described as a ‘silyl’ or ‘silane’ group.

As used herein, “alkoxy” refers to any —O—R group, where R (and R′ foran ether, below) may independently be H, alkyl, siloxy or aryl. Examplesof alkoxy and siloxy groups include those with from 1 to 50 carbon orsilicon atoms in a linear or branched chain, for example methoxy orethoxy, or longer alkyl groups. Alkoxy groups include ethers (—R—O—R′—),alcohol (—OH) or alkoxide (—R—O-metal) or the like. An alkyl groupcomprising an alkoxy substituent group may be referred to as an‘alkylalkoxy’ group. An alkyl group comprising an Si heteroatom, and analkoxy, or a siloxy group may be referred to as an alkylsiloxy, orsilylsiloxy group.

As used herein, “carbonyl” includes aldehyde (R—COH), ketone (RCOR′),ester (RCOOR′), acyl (RR′C═O), carboxyl, thioester (COSR′), primaryamide (CONH₂), secondary amide (CONHR′), tertiary amide (CONR′R″) or thelike.

R′, R″, R′″ may be alkyl chains that contain between 1 and 50non-hydrogen atoms such as C, N, O, S, Si, B or P that may be branchedor unbranched, that may be acyclic or cyclic, and that may contain anypermutation of heteroatomic substituents such as N, O, S, Si, B orhalogen.

As used herein, “aryl” refers to a group or substituent derived from anaromatic ring compound where one or more hydrogen atoms are removed fromthe ring. An aryl group may alternately be referred to as an aromaticgroup. An aryl group may comprise a single atom species in the ring(e.g. all ring atoms may be carbon, such as in a phenyl ring—acarbocycle′) or may comprise one or more heteroatoms in the ring—a“heteroaryl”. An aryl group may be polycyclic. The carbocyclic,heterocyclic or polycyclic aryl group may comprise one or moresubstitutent groups (a substituted aryl) or be unsubstituted (anunsubstituted aryl). A carbocyclic aryl group may be substituted orunsubstituted phenyl or the like. A carbocyclic aryl group may bepolycyclic.

A heterocyclic aryl group may be substituted or unsubstituted pyrrole,furan, thiophene, imidazole, pyrazole, oxazole, isoxazole, thiazole,isothiazole, triazole, furazan, oxadiazole, thiadiazole, dithiazole,tetrazole, pyridine, pyran, thiopyran, diazine, oxazine, thiazine,dioxine, dithiine, triazine, tetrazine, or the like. A polycyclic arylgroup may be substituted or unsubstituted indole, isoindole, quinolone,isoquinoline, benzofuran, benzothiophene, acridine, dibenzothiophene,carbazole, dibenzofuran or the like.

Compounds according to various embodiments of the invention may includeone or more of the following:

Each R₁, R₂ may be independently selected from a group comprising H orF.

Each R₄ may each be independently selected from a group comprising oneor more than one of thiophenyl, substituted thiophenyl, benzyl,substituted benzyl,

Each R₅ may be independently selected from a group comprising: H,methyl, ethyl, propyl, butyl, tert-butyl, thiophenyl, substitutedthiophenyl, benzyl, substituted benzyl, —CH═CH—, —CH═CH—, —OCH₃, CO₂H.

Substituent groups of a substituted thiophene or substituted benzylgroup may include —CN, methyl, ethyl, propyl, butyl, tert-butyl.

R_(6a) and R_(6b), or R_(6b) and R_(6c), or R_(7a) and R_(7b), or R_(7b)and R_(7c) may each be a) —CH═CH— and fused to form a ring; or b)—CH₂—CH₂— and fused to form a ring; or c) —O—CH₂— and fused to form aring;

One or more than one of: R_(6a), R_(6b), R_(6c); and/or R_(7a), R_(7b),R_(7c); and/or R_(9a), R_(9b), R_(9c), R_(9d), R_(9e); and/or R_(10a),R_(10b), R_(10c), R_(10d) may each independently be selected from agroup comprising one or more of: H, Cl, Br, F, —CF₃, —CN, —NO₂, methyl,ethyl, propyl, iso-propyl, butyl, sec-butyl, iso-butyl, tert-butyl,saturated or unsaturated alkyl that is linear or branched with 5-12carbons, —Si(R₁₁)₃, thiophene, substituted thiophene, benzyl,substituted benzyl, —CH₂—CH₂—, —CH═CH—, —CH═CH₂, —OCH₃, —COH, —OH,—CO₂H, —COCH₃, —CO₂Y, —C(CH₃)₂OH, —Si(CH₃)₃, —CH₂CH₂OCH₃, —CH₂CH₂OH,—N(CH₃)₂, —CO₂CH₃, —OCH₂OCH₃, —SO₂CH₃, —OCH₂C(CH₃)₃, —OCH₂CH(CH₃)₂,—OC(CH₃)₃, —OCH═CH₂, —O(CH₂)₄CN, —O(CH₂)₄OH, —O(CH₂)₃OH, —C(CH₃)₂OH,—OCH₂)₂OCH₃,

In some embodiments, each R₁₁ of —Si(R₁₁)₃ may be independently selectedfrom the group comprising R or —O—R, and wherein R is linear orbranched, non-aromatic monocyclic or polycyclic, substituted orunsubstituted alkyl group of 1 to 5, 1 to 10, 1 to 15 or 1 to 20carbons. In some embodiments, each R may be a heteroalkyl groupcomprising one or more of O, S, N or Si, or each R may be a saturated orunsaturated alkyl that is linear or branched with 1-12 carbons, or eachR may be a substituted or unsubstituted methyl, ethyl, propyl,iso-propyl, butyl, sec-butyl, iso-butyl, tert-butyl, pentyl or hexyl.

In some embodiments, for a compound according to Formula IA and IB, R₁and R₂ are H or F, Z and X are each S, R₄ may be

andR_(6a), R_(6b), and R_(6d) may independently be —OCH₃, H, —C(CH₃)₃ or—Si(R₁₁)₃,

In some embodiments, for a compound according to Formula IIA and IIB, R₁and R₂ are H or F, Z is O, R_(10a), R_(10b), R_(10c) and R_(10d) mayindependently be —OCH₃, H, —C(CH₃)₃

andR₄ may be

In some embodiments, for a compound according to Formula IIA and IIB,where R₁ and R₂ are F and Z is O and all of R_(10a), R_(10b), R_(10c)and R_(10d) are H, R_(9c) is not an alkyl chain according to C₄H₉, C₈H₁₇or C₁₂H₂₅.

Examples of chromophores according to Formula IA/B and Formula IIA/B areshown below. Synthetic schema, photostationary state and sensitivityindex for these and other chromophores according to Formula IA/B andFormula IIA/B are described in commonly owned PCT ApplicationPCT/CA2012/000910. The open-ring isoform (isoform A) is illustrated, andconditions to open and close the rings of the appropriate isoform areindicated herein (e.g. exposure to light, or application of voltage).

Combinations of chromophores for inclusion in switching materials of anoptical filter according to various embodiments of the invention may beselected to provide a particular LT range and/or particular colour ofthe optical filter in a dark or light state.

Solvent:

A solvent component of a switching material may have one or more of thefollowing characteristics: boiling point of about 150° C. or greater,vapour pressure of about 0.001 mmHg or less at 20° C., Yellowness Index(YI) of about 6 or less; a flash point of about 80° C. or greater, amelting point of about 40° C. or less, is compatible with components ofa switching material or coatable formulation, and does not interferewith darkening or fading of the switching material. The solventcomponent may be a mixture of one or more than one solvents. Examples ofsolvents include triglyme, tetraglyme, propylene carbonate, ethylenecarbonate, 2-butylene carbonate, delta-valerolactone, formamide,3-methyl-2-oxazolidone, phthalide, tetramethylurea, dimethyl-2-methylglutarate, diethyl succinate, triethylene glycol di-2-ethyl butyrate,triethylene glycol bis(2-ethylhexanoate, butyrolactone, cyclopentanone,ethylene glycol phenyl ether; diethylene glycol monobutyl ether,2(2-butoxyethoxy)ethyl acetate, diethyl adipate, dimethyl adipate,2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, propylene glycoldiacetate, dibutyl itaconate, dimethylglutarate or the like. The one ormore solvents may comprise from about 30% to about 90% (wt %) of theswitching material, or any amount or range therebetween. In someembodiments, the solvent is optically clear, or substantially opticallyclear, and the one or more supporting electrolyte, rheology modifiers,gelling agents, polymers, co-solvents, accelerants, hardeners, epoxidesand other components of a switching material or composition are solublein the solvent

Supporting Electrolyte:

Supporting electrolytes may include alkali metal salts,tetralkylammonium salts or the like. Examples include tetrabutylammoniumtetrafluoroborate, tetrabutylammonium hexafluorophosphate,tetrabutylammonium perchlorate, lithium bis(trifluoromethanesulfonimide), tetrabutylammonium bis((trifluoromethyl) sulfonyl)imide,triflate, lithium bis(oxatlato)borate, lithium perchlorate or the like.The one or more electrolytes may be present in an amount from about 0.1%to about 10% (by weight) or any amount or range therebetween, forexample 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, or 9%, or any amount or rangetherebetween.

Polymer:

The switching material may comprise one or more polymers. The one ormore polymers may be a rheology modifier, a crosslinkable polymer, orboth a rheology modifier and a crosslinkable polymer. A rheologymodifier may increase the viscosity of the switching material tofacilitate coating of the switching material on a substrate, or into amold or die. Examples of one or more polymers include polyvinyl alcohol(PVOH), polyvinyl acetate (PVA), polyvinylbutyral (PVB), poly(methylmethacrylate) (PMMA), nitrile rubber (NBR), polyvinylpyrrolidone (PVP),polyvinylidene fluoride (PVDF), poly(dimethylsiloxane) (PDMS),poly(ethyl methacrylate) (PEMA), NBR, hydroxypropyl cellulose, PEG-DMA(poly(ethylene glycol) dimethacrylate), PHEMA (poly(2-hydroxyethylmethacrylate), Plexiglas™ G-UVT acrylic, polychloroprene, polybutadiene,PDMS-g-PEG (PEG-modified PDMS), PEO (polyethylene oxide), PEG-MEMA(PEG-methylether methacrylate), silicones, PDMS, PPGMA (poly(propyleneglycol), EGDMA (ethylene glycol dimethacrylate), PVDC (polyvinylidenechloride), PVC (polychlorovinyl), PVDC-PVC, cyclo olefin copolymer(APEL™), carboxymethyl cellulose (CMC), SOLEF™ 21520, SOLEF™ 21508,zein, polyisobytulene-600, poly(ethylene-co-methacrylic acid (EMAA,SURLYN™ 60), polyethylene-co-(ethylacrylate), ethylacrylate,poly(vinylidene chloride-co-vinyl chloride), polyisoprene, polybutene,poly(sodium 4-styrene sulfonate), HEMA (hydroxyethyl)methacrylate orcombinations thereof, or copolymers thereof. Cross-linkable polymerscomprise one or more pendant —OH groups, and may be a homopolymer orcopolymer. Examples of cross-linkable polymers include PVOH, PVA, PVBand PEO. One or more polymers may be present in an amount of about 0.5wt % to about 20 wt %, or any amount or range therebetween, for example1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 wt%. Examples of PVB preparations that may be used in compositions orformulations according to various embodiments of the invention includeone or more of B60H (Kuraray; MW of about 50-60K), B90 (Butvar, MW ofabout 70-100 K) and B72 (Butvar, MW of about 170-250 K).

One or more sol-gels may also be included in a switching material; asol-gel may be a rheology modifier. Examples of sol-gels includesilicon-oxygen based sol-gels, aluminum-oxide based sol-gels orcombinations thereof. The one or more polymers or sol-gels may bepresent in an amount from about 0.1% to about 10% (by weight) or anyamount or range therebetween, for example 1, 2, 3, 4, 5, 6, 7, 8, or 9%,or any amount or range therebetween.

The switching material may comprise components (hardeners, accelerants,crosslinkers or the like) to facilitate cross-linking of the switchingmaterial before, during or after coating on a substrate layer orsurface.

Cross-Linker:

A cross-linker (cross-linking agent) may comprise two or more reactivegroups; reactive groups may independently be, for example, aldehyde,epoxide, isocyanate, silane or the like. Examples of crosslinking agentsinclude aldehyde, isocyanate, melamines, phenolic resins or the like. Ahardener may be used with some crosslinking agents comprising an epoxidereactive group. Examples of aldehyde crosslinkers includeterephthalaldehyde and the like, Examples of epoxides include DER736,DER732 (both from Dow Chemical), bisphenol A diglycidyl ether (BADGE),1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidylether, 1,2,5,6-diepoxycyclooctane, resorcinol diglycidyl ether,tris(4-hydroxyphenyl)methane triglycidyl ether or diglycidyl1,2-cyclohexanedicarboxylate and the like. Examples of isocyanatecrosslinking agents include aromatic and aliphatic diisocyanates;examples of aliphatic diisocyanates include hexamethylene diisocyanate(e.g. DESMODUR™ N100, N3300A, N3600), isophorone diisocyanate, methylenedicyclohexyl diisocyanate, xylylene diisocyanate, cyclohexanediisocyanate, tetramethyl xylylene diisocyanate, isopropenyldimethylbenzyl isocyanate, trimethylhexamethylene diisocyanate,norbornane diisocyanate or the like. Examples of aromatic diisocyanatesinclude diphenylmethane diisocyante, toluene diisocyanate, p-phenylenediisocyanate, naphthalene diisocyanate or the like. The cross linker maybe present in a switching material in an amount of about 0.01% to about10%, or any amount or range therebetween, for example 0.02, 0.04, 0.06,0.08, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 wt %, or any amount orrange therebetween.

Hardeners:

A hardener (curing agent”) may be an anhydride, for example MHHPA(methylhexahydrophthalic anhydride) THPA (tetrahydropthalic anhydride),MTHPA (methyltetrahydropthalic anhydride), HHPA (hexhydropthalicanhydride), 4-methylhexahydrophthalic anhydride or the like. A hardenermay be present in a switching material in an amount of about 0.5% toabout 10%, or any amount or range therebetween, for example 1, 2, 3, 4,5, 6, 7, 8, or 9 wt %.

Accelerant:

examples of accelerant (“catalyst”) used with materials comprising anepoxy reactive group may include AMC-2, AMC-3, ATC-3 (AMPAC FineChemicals), Zinc 2-ethyl hexanoate (99%, or 80% in mineral spirits), AC8(Available from Broadview), CXC1612 or CXC1613 (King Industries),1,4-diazabicyclo[2.2.2]octane (DABCO), HCl, p-toluenesulfonic acid,potassium t-butoxide, Tyzor ZEC (Dorf-Ketal), Tyzor AA75 (Dorf-Ketal),Titanium tetraisopropoxide, Copper (II) chloride. Where the crosslinkeris an aldehyde, the accelerant may be an acid, such as a Lewis acid.Examples of accelerants that may be used with materials comprising anisocyanate reactive group may include dibutyltin dilaurate, dibutyltindiacetate, dibutyltin oxide, transition metal (e.g. Mn, Sn, V, Bi, Zn,Co, Zr, Al, Cr, Ti, Cu) complexes of acetylacetonate, octanoate, chelate(e.g. metal chelates from King Industries) or the like. The accelerantmay be present in a switching materialin an amount of about 0.001% toabout 1%, or any amount or range therebetween, for example, 0.01, 0.05,0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9 wt %.

Co-Solvent:

a co-solvent may be used to dilute a switching material for coating on asubstrate. A co-solvent is compatible with other components of theformulation—for example, other components are soluble in, and unreactivewith, the co-solvent. The co-solvent may be, for example, toluene,tetrahydrofuran, methyl ethyl ketone, or ethyl acetate. A co-solvent maydilute a switching material from about 5% to about 50%, or any amount orrange therebetween. After coating, the co-solvent may be removed (e.g.by evaporation) before applying a second substrate, or another layer ofswitching material, or before incorporating the optical filtercomprising the switching material into a composite optical filter.

Other components of the switching material may include a tinting agent,a UV blocker (e.g. benzotriazoles, benzophenones or the like), a UVstabilizer (e.g. HALS) or the like, present in an amount from about 0.1%to about 10% or any amount or range therebetween.

Preparation of Optical Filters

An optical filter according to various embodiments of the invention maybe manufactured by any suitable process, for example, wet-coating aswitching material onto one or more substrates, allowing for aroll-to-roll manufacturing process, and avoiding sputter-coating orvapour deposition, or other more complex and/or more expensiveprocesses. The switching material may be formulated for application as aliquid, gel or sol-gel, and thickened, set or cross-linked afterapplication, forming a layer on the transparent substrate or layer. Anoptical filter may be applied to the surface of a display, and may beaffixed using an adhesive. Switching material may be directly applied toa surface of, or to be used in, a display, and laminated with asubstrate.

The switching material may be a thermoplastic, thermosetting (uncured)or thermoset (cured) material. The switching material may be aviscoelastic material (an “elastomer”). Where the switching material isa thermoset material, it may be cured by heating, exposure to UV light,chemical reaction, irradiation, electron beam processing or acombination thereof. The switching material may be coated onto anarticle using coating techniques such as dipping, spraying,spin-coating, powder coating or the like. The switching material, or oneor more components of the switching material, may be formed intopellets, chips or flakes and mixed with other components of theswitching material and/or a thermoplastic material (e.g. in a screwmixer) and extruded to form one or more layers or films. The mixerand/or extruder may be heated. Alternately, the extruded material mayitself be pelletized, for subsequent blending with other, compatible,thermoplastic materials and extruded in a second extruder to produce atransparent, translucent or opaque film, or injection molded into a moldto produce a transparent, translucent or opaque article. For operation,the switchable optical filter may be a film and applied to a surface ofa display, or offset from a surface of the display by a suitabledistance (e.g. an air gap). The film may be flexible and suitable forcutting to a desired shape; alternately, the film may be provided in oneor a set of standard sizes and a suitable size selected. An adhesive maybe used to affix the film to a surface of the display. Once secured, thelight source(s) may be connected to the electrical system and a switchprovided for operation.

PCT Publication WO2010/142019 describes methods for making an opticalfilter. Generally, a first substrate or layer is provided and theswitching material is coated or deposited on a first side of thesubstrate or layer. A second layer may be applied on top of theswitching material (and may comprise a non-removable portion of theoptical filter, or may be a peel-away layer to facilitate laterplacement of the optical filter on a display surface), or the switchingmaterial may be placed in contact with a switching material applied to asecond substrate, to provide an optical filter comprising 2 layers ofswitching material.

In one embodiment, the switching material has a high viscosity at roomtemperature and is made into a lower-viscosity liquid by heating toallow it to be applied or coated onto the substrates. In one embodiment,the switching material is heated and pressed between the substrates.According to another embodiment of the invention, the switching materialis first cast as a liquid and then further treated to increase theviscosity of the material to form a gel. For example, the switchingmaterial can be dried wherein the solvent or co-solvent is evaporatedfrom the switching material. In other embodiments, the switchingmaterial is cured to increase the viscosity to form a gel. Curing theswitching material may be accomplished with temperature, UV light or aninitiator (catalyst). Other methods of curing such as exposure toelectron beams may be possible with different formulations. The gelledswitching material can then adhere to both first, second, or first andsecond substrates or layers to form an integral structure.

An optical filter may further comprise additional components such astinted glass (e.g. grey, brown, bronze, reflective or other glass),static cutoff filters (coloured filters for selective transmission ofvisible light). In some embodiments, the optical filter may comprise oneor more UV blocking components (UV blocker, or UV blocking layer) toblock some or a substantial amount of the UV light that the device ofthe invention is exposed to in order to counteract UV light-induceddegradation of the switching material or to prevent ‘escape’ of UV lightfrom the optical filter, and expose a user to UV light. The UV blockermay be incorporated in the substrate or applied as a layer on asubstrate, or applied as a layer of a device or apparatus according tovarious embodiments of the invention. The layer may be a depositedorganic or inorganic material or combination thereof, or may be a film.A UV blocker may be deposited by any suitable method, for examplechemical vapor deposition, physical vapor deposition, (e.g. sputtering,electron beam evaporation, and ion plating), plasma spray techniques,sol-gel processes or the like. In some embodiments, an adhesive employedto affix one or more optical filters may be, or comprise, a UV blocker.Examples of UV blockers include WO₂, WO₃, ZnO, CdO or a combinationthereof; thin film materials (e.g. a dichroic filter) with thickness andindex of refraction chosen so as to reflect or absorb UV light; a UVabsorbing polymer or a polymer comprising a light-absorbing or UVstabilizing component. Examples of such polymers include polyethylenes,polypropylenes, polybutylenes, epoxies, acrylics, urethanes, vinylsincluding polyvinyl chloride, poly(vinyl butyral), poly(vinyl alcohol),acetates, polystyrenes, polyimides, polyamides, fluorocarbon polymers,polyesters, polycarbonates, poly(methyl methacrylate), poly(ethylmethacrylate), poly(vinyl acetate), or co-polymers or polymer blendsthereof. In some embodiments, the substrate is PET comprising a UVblocking additive (e.g. XST6578 from DuPont Teijin). Such a substratemay be a UV blocking layer. In some embodiments, the substrate may haveapplied to one or both sides of it a UV, selective UV, IR, selective IRor selective VIS light blocking layer; the blocking layer may be in theform of a coating or film. A selective UV, VIS or IR blocking layerselectively blocks (absorbs or reflects) a portion of UV, VIS or IRlight, respectively. Examples of UV blocking films that may be appliedinclude EnergyFilm™ (described in WO2002/018132) and EnerLogic™(described in WO2009/087575). Examples of UV blocking layers includeoptical clear pressure sensitive adhesives with UV blocking components(e.g. 8172PCL from 3M). In one embodiment, the UV blocker blocks most ofthe UV light below about 350 nm, or below about 365 nm, or below about375 nm, or below about 380 nm, or below about 385 nm, or below about 400nm. In some embodiments the UV blocking layer may comprise PVB. In someembodiments, the optical filter comprises a switching material that istransitionable to a dark state when exposed to UV light that is greaterthan about 350 nm, or greater than about 365 nm, or greater than about375 nm, or greater than about 385 nm, or greater than about 385 nm. Insome embodiments, the optical filter may comprise an IR blockingcomponent, or IR blocking layer. Examples of IR blocking layers includetransparent metal oxide layers, XIR films (Southwall), such as XIR-75Blue.

Once the filter has been made, it can be cut to size, sealed around theperimeter if necessary, and a light source affixed (e.g. strips or rowsof LEDs, or individual LEDs inserted or affixed along the edge of theoptical filter), or the optical filter mounted within a frame, the framemay comprise a light source with electrical connectors for operation ofthe light source and connection to control electronics. The LEDs in turnmay be provided with an electrical connection (s) for connecting to aspower source.

Glass Lamination

An optical filter may be laminated by placing it between two layers ofadhesive resin (PVB or EVA sheet), and this in turn placed between twolayers of glass (e.g. 3 mm float glass) The assembly may be passedthrough a press roll or pressed between plates at an elevatedtemperature (about 90° C. to about 140° C.—pressure and temperature maybe increased and decreased over several steps), or may be placed in abag (rubber), with an initial bonding at a temperature of about 70°C.-110° C., while applying a vacuum to remove air between the layers. Asecond bonding step is then performed at a temperature of about 120°C.-150° C., with pressure (e.g. about 0.95 to about 1.5 MPa in anautoclave). The overall thickness of the laminated glass is dependent,in part on the thickness of the various layers, generally an overallthickness of about 6.3 to about 6.6 mm is preferred.

Control Electronics

For operation, the one or more light sources are connected to a powersource capable of providing sufficient power to illuminate the switchingmaterial, and in some embodiments the display and the switchingmaterial, with an intensity sufficient to effect a transition of theswitching material from a dark to a faded state or from a faded to adark state. Control electronics may be used to switch the power on oroff based on input from a user or some other input, and can also be usedto modulate the power to a suitable level (e.g. to control brightness ofthe display. Control electronics may be configured to turn the UV lightsource and display on and off as desired. In one embodiment, the UVlight source may be coupled to the display and/or VIS light source sothat when the display and/or VIS light source is turned on, the UV isoff, and the visible light fades the switching material, enhancing thevisibility of the display information. Where the switching material iselectrochromic, additional electrical connectors connect electrodes incontact with the switching material to a power source that may be turnedon to electrofade the switching material. Configurations for connectingan electrochromic switching material to a power source are described incommonly owned applications WO2010/142019 and U.S. 61/661,690.

Control electronics may include a switch for manual, automatic, orsemi-automatic operation of the light sources. The one or more switchesmay be, for example, a transistor, a relay or an electromechanicalswitch. In some embodiments, the control circuit may further comprise anAC-DC and/or a DC-DC converter for converting the voltage from thevoltage source to an appropriate voltage for the light source. Thecontrol circuit may comprise a DC-DC regulator for regulation of thevoltage. The control circuit may further comprise a timer and/or othercircuitry elements for applying electric voltage to the optical filterfor a fixed period of time following the receipt of input. A switch maybe activated manually or automatically in response to predeterminedconditions, or with a timer. For example, control electronics mayprocess information such as time of day, ambient light levels detectedusing a light sensor, user input, stored user preferences, occupancylevels detected using a motion sensor, or the like, or a combinationthereof, the control electronics configured to activate switches forapplying power to the light source in response to the processedinformation in accordance with predetermined rules or conditions, or atimer. In one embodiment, the power control electronics comprises auser-activated switch that passes the DC voltage from the power sourcesubstantially directly to the light source. A user-activated switch maybe a ‘normally-open’, or ‘normally-closed’ switch, for example apush-button switch. A switch may be configured to remain closed for apredetermined amount of time following actuation, thereby facilitatingapplication of voltage to the light source for sufficient time to effecta state transition of the optical filter.

Where the switching material is electrochromic, the voltage to beapplied for transitioning one or more of the optical filters may bedependent on factors such as the switching material composition and/orthe resistivity of the electrodes in contact with the electrochromicswitching material. The voltage may be fixed or it may be controllableby the control system. Voltage applied to an optical filter may be fromabout 0.1 V to about 20 V, or any amount or range therebetween, forexample, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18or 19 V. In some embodiments, the amount of voltage applied is fromabout 0.1 V to about 5V, or from about 1V to about 10 V, or from about1.0 V to about 2.2 V, or from about 0.5V to about 3V, or from about 1.2Vto about 2.5 V, or from about 1.8 V to about 2.1 V, or any amount orrange therebetween. In some embodiments, the voltage applied is lessthan about 12 V, or less than about 6 V, or less than about 3 V or lessthan about 2.5 V, or about 2 V.

In some embodiments, a switching material comprising a compoundaccording to Formula II may be faded with application of a voltage ofabout 2.2V. In some embodiments, a switching material comprising acompound according to Formula I maybe faded with application of avoltage of about 2.0 V.

Commonly owned application PCT/CA2013/000054 describes composite opticalfilters with two or more optical filter; each optical filter may includethe same, or different chromophore, in the switching material. Asindicated above, chromophores of Formula I and II may necessitate theuse of different voltages to effect the electrochemical switch from darkto faded state—this may preclude the inclusion of both Formula I andFormula II chromophores in the same switching material where theswitching material is to be faded with electricity—it is not possible tosimultaneously apply two different voltages to a switching material, andif the chromophores are in the same switching material, not possible toisolate one from another to prevent damage from over-voltage. Bycombining chromophores of Formula I and Formula II in the same layer ofswitching material as per embodiments described herein, and coupling theoptical filter with the switching material in an apparatus comprising alight source that provides light of suitable wavelength to fade, darken,or fade and darken the switching material, the present disclosureprovides an advance over the art by providing controllable darkening ofwhat may previously have been considered a passively darkening material.Inclusion of one or more selective filters in the apparatus to preventegress of the controllable light (e.g. to isolate a user from a UV lightsource), or prevent ingress of external light (e.g. to preventuncontrolled fading or darkening of the switching material) may providea further advantage by isolating the optical filter comprising theswitchable material.

Testing and Use of Optical Filters

Performance of an optical filter may be tested by conducting studiesusing standard techniques in the art, for example, measurement of LT,haze, switching speed, photostability, and/or durability. WO2010/142019describes methods, equipment and techniques that may be used to assessthe performance of optical filters. The optical filters of the presentinvention can be incorporated into a variety of applications. Inparticular, optical filters of the invention are especially applicablein systems where it is desirable to dynamically control and filterlight. The optical filters of the invention can be used as-is or can belaminated onto another substrate such as glass or polycarbonate.Selection of a particular set of characteristics (e.g. LT in the fadedand dark states) may be dependent on the use of the optical filter.

Synthesis of Ring-Closed or Ring-Open Isomer of Compounds:

Where a preparation of a ring-closed isomer is desired (as an isolatedcompound, e.g. for NMR studies, or some syntheses), the compound may bedissolved in CH₂Cl₂ and placed in a quartz glass cell. The solution wasirradiated at 365 nm for 10 minutes, or until no further change inabsorbance is observed. Solvent was evaporated off under reducedpressure and the product purified using HPLC to afford the respectivering-closed isomer. Where a preparation of a ring-open isomer is desired(as an isolated compound, e.g for NMR studies, or some syntheses), thecompound may be dissolved in CH₂Cl₂ and placed in a quartz glass cell asdescribed. The solution may be irradiated with visible light comprisinga wavelength of ˜500 to 700 nm for 10 minutes, or until no furtherchange in absorbance is observed. Solvent may be evaporated off underreduced pressure and the product purified using HPLC to afford therespective ring-open isomer.

Example 1: Preparation of an Optical Filter

Switching material comprising 10 wt % chromophore (1:1S158: S161) insolvent (dimethyl 2-methylpentanedioate) was prepared and placed in aglass cell testing cell (50 micron thick chamber) and sealed. Theswitching material was darkened with simulated sunlight (SolarSimulator-ScienceTech), or UV (365 nm) light, and transmission spectrawere obtained (using an Ocean Optics spectrophotometer) for each state(FIG. 13). The switching material was then faded with a low-pressuresodium lamp (575-585 nm light and transmission spectra obtained). In afully faded state, transmission is high and the switching material istransparent. With exposure to a UV light source (simulated sunlight or365 nm source), the switching material attains a dark state with a lighttransmittance (LT_(A)) in a faded state of 84.4%, 6.8% when darkenedwith simulated sunlight (contrast ratio of about 12), and 0.10 whendarkened with 365 nm UV light (contrast ratio of 832).

The present invention has been described with regard to one or moreembodiments. However, it will be apparent to persons skilled in the artthat a number of variations and modifications can be made withoutdeparting from the scope of the invention as defined in the claims.Therefore, although various embodiments of the invention are disclosedherein, many adaptations and modifications may be made within the scopeof the invention in accordance with the common general knowledge ofthose skilled in this art. Such modifications include the substitutionof known equivalents for any aspect of the invention in order to achievethe same result in substantially the same way. Numeric ranges areinclusive of the numbers defining the range. In the specification, theword “comprising” is used as an open-ended term, substantiallyequivalent to the phrase “including, but not limited to,” and the word“comprises” has a corresponding meaning. As used herein, the singularforms “a”, “an” and “the” include plural referents unless the contextclearly dictates otherwise. Citation of references herein shall not beconstrued as an admission that such references are prior art to thepresent invention. Citation of references herein does not constitute anyadmission as to the contents or date of the references. All publicationsare incorporated herein by reference as if each individual publicationwas specifically and individually indicated to be incorporated byreference herein and as though fully set forth herein. The inventionincludes all embodiments and variations substantially as hereinbeforedescribed and with reference to the examples and drawings.

It is contemplated that any embodiment discussed in this specificationcan be implemented or combined with respect to any other embodiment,method, item, composition or aspect of the invention, and vice versa.

What is claimed is:
 1. An apparatus comprising: a. a switchable opticalfilter comprising a layer of switchable material, the switchablematerial comprising: i. a compound according to Formula IA/B that isreversibly convertible between a ring-open isomer A and a ring-closedisomer B:

ii. a compound according to Formula IIA/B that is reversibly convertiblebetween a ring-open isomer A and a ring-closed isomer B:

or iii. a compound according to Formula IA/B and a compound according toFormula IIA/B; b. a first light source providing light of a wavelengththat causes the switchable material to transition from a first state toa second state, or the second state to the first state, the first statehaving a greater light transmittance than the second state; and c. aswitch for controlling activation of the first light source.
 2. Theapparatus of claim 1, wherein the first light source provides light witha wavelength of less than about 450 nm or from about 350 to about 420nm.
 3. The apparatus of claim 1 wherein the first light source provideslight that causes the switchable material to transition from the firststate to the second state.
 4. The apparatus of claim 1, furthercomprising one or more UV blocking layers, a light dispersing layer, orone or more UV blocking layers and a light dispersing layer.
 5. Theapparatus of claim 1, further comprising a second light source.
 6. Theapparatus of claim 5 wherein the second light source causes theswitchable material to transition from the second state to the firststate.
 7. The apparatus of claim 5 wherein the second light sourceprovides light with a wavelength of from about 450 nm to about 650 nm,or light with a wavelength of from about 575 to about 650 nm.
 8. Theapparatus of claim 1 wherein the switchable optical filter istransitionable from the first state to the second state with applicationof 350 to 420 nm light, and transitionable from the second state to thefirst state with application of 450 to 650 nm light, or light with awavelength of from about 575 to about 650 nm, or electricity.
 9. Theapparatus of claim 1 wherein the switching material is transitionablefrom the first state to the second state, and wherein the second statehas 1% or less of light transmittance with application of UV light. 10.The apparatus of claim 1, wherein the first light source is adjacent toone or more edges of the switchable optical filter.
 11. The apparatus ofclaim 1 wherein the first light source is adjacent to one or moresurfaces of the switchable optical filter.
 12. A display apparatuscomprising: a. a display; and b. a switchable optical filter comprisinga switchable material, the switchable material comprising i. a compoundaccording to Formula IA/B that is reversibly convertible between aring-open isomer A and a ring-closed isomer B:

ii. a compound according to Formula IIA/B that is reversibly convertiblebetween a ring-open isomer A and a ring-closed isomer B:

or iii. a compound according to Formula IA/B and a compound according toFormula IIA/B.
 13. The display apparatus of claim 12, further comprisinga first light source and optionally a second light source, the first andoptional second light sources providing light of a wavelength thatcauses the switchable material to transition from a first state to asecond state, or the second state to the first state, the first statehaving a greater light transmittance than the second state.
 14. Thedisplay apparatus of claim 13 wherein the first light source, the secondlight source, or the first and the second light sources are located at aperiphery of the optical filter.
 15. The display apparatus of claim 13wherein the first light source, the second light source or the first andthe second light sources are on a plane parallel or substantiallyparallel to the display.
 16. The display apparatus of claim 13 whereinthe first light source, the second light source, or the first and thesecond light sources are offset from the plane of the display, the planeof the switchable optical filter, or the plane of the display and theplane of the switchable optical filter.
 17. The display apparatus ofclaim 13 wherein the first light source provides light with a wavelengthof less than about 450 nm, or from about 350 to about 420 nm, and thesecond light source provides light with a wavelength of from about 450nm to about 650 nm, or light with a wavelength of from about 575 toabout 650 nm.
 18. The display apparatus of claim 12 further comprising alight dispersing layer, a UV blocking layer, or a light dispersing layerand a UV blocking layer.
 19. The display apparatus of claim 12 whereinthe switchable optical filter is spaced apart from a surface of thedisplay.